An old roof of a building is typically renewed when water leaks or heat insulation deteriorates. Recently, however, a roof may be renewed to install a photovoltaic module for photovoltaic power generation.
In general, a roof panel is manufactured as a sandwich panel type in which a heat insulator is interposed between two metal panels, or manufactured as a single panel type by roll-forming a single metal plate. Most roof panels have a fitting projecting bar and an elastic clip at both ends thereof in a width direction regardless of the type of roof panel, with the elastic clip connected and fitted to a fitting projecting bar of a neighboring panel in the width direction.
Due to factory space limitations or logistical difficulties, a roof panel is cut to an arbitrary length and then transported. Therefore, when a roof is being constructed, a plurality of roof panels needs to be connected in a longitudinal direction to have a length corresponding to the length of the roof. However, since there is no structure that allows for the superimposition of neighboring panels at the end portions in the longitudinal direction of the roof panel, unlike at the end portions in the width direction, the roof panels need to be connected in the longitudinal direction by using additional connecting members. Using additional connecting members makes the process inconvenient and time consuming, and furthermore, allows for water leaks.
In addition, the presence of a plurality of connecting portions of the roof panels on the roof reduces the structural safety of the roof.